The behavior of the xenon nanoinclusions/bubbles in the uranium dioxide (UO2) matrix and their influence on its swelling were investigated through atomistic simulation techniques. The pressure in bubbles of less than 2 nm in diameter, calculated using a virial equation that takes into account the xenon/matrix interactions, is larger than the pressure calculated in simulations of the equivalent density and temperature of super critical bulk xenon. The radial distribution function of confined xenon is characteristic of a dense (*ρ* > 4 g/cm3) glassy phase. The swelling of the UO2 induced by the intragranular bubbles is proportional to the Xe/U ratio but independent of the temperature.

We present a review of a few research topics developed within the "Theory and Atomistic Computer Simulation" Department at CINaM. The bottom line of the scientific activity is to use up–to–date theoretical and computer simulation techniques to address physics and materials science problems, often at the nanometric scale, in close contact with experimental groups. It ranges from the study of the structure and properties of molecular systems for organic electronics to metallic clusters and alloys, magnetic oxides, nuclear fuels and carbon–based nanostructures. These studies are motivated by fundamental research questions as well as more applied goals including environmental and energy issues, or information technologies. This broad spectrum of activities requires a large range of techniques, from theory and ab initio calculations to semi–empirical models incorporated in Monte Carlo or molecular dynamics simulations.

VL - 9 IS - 3-7 ER - TY - JOUR T1 - An atomistic modelling of the porosity impact on UO2 matrix macroscopic properties JF - Journal of Nuclear Materials Y1 - 2011 A1 - Andrei Jelea A1 - Colbert, M. A1 - F. Ribeiro A1 - G. Tréglia A1 - Roland Jean-Marc Pellenq AB -The porosity impact on the UO_{2} matrix thermomechanical properties was investigated using atomistic simulation techniques. The porosity modifies the thermal expansion coefficient and this is attributed to pore surface effects. The elastic moduli at 0 K and at finite temperature decrease with porosity, this variation being well approximated using affine functions. These results agree with other mesoscale model predictions and experimental data, showing the ability of the semiempirical potential atomistic simulations to give an overall good description of the porous UO_{2}. However, the surface effects are incompletely described.

VL - 415 IS - 2 JO - Journal of Nuclear Materials ER -